Graft polymerization of thioated hydroxy containing polymers with ethylenically unsaturated monomers



United States Patent 35 Claims. (Cl. 260-17 ABSTRACT OF THE DISCLOSUREPeroxidic initiated graft polymerization process using as substratesdithiocarbonate or monothiocarbonate derivatives of hydroxylgroup-containing or group hydrolyzable to a hydroxyl group-containingsynthetic polymers and the copolymers produced by the process.

This invention relates to processes for producing a copolymer of anethylenically unsaturated monomer with substantially water insolublesubstrates as defined herein by periodic free radical initiated graftpolymerization and to the novel copolymers produced thereby. Thisapplication is a division of application S.N. 563,055, filed July 6,1966, as a continuation-in-part of now abandoned applications S.N.271,491 and 271,492, filed Apr. 8, 1963; 339,324, filed Jan. 22, 1964;345,577, filed Feb. 18, 1964; 432,816, 432,825, 432,834, 432,853,432,855, 432,902 and 432,904, filed Feb. 15, 1965; and 491,395, filedSept. 29, 1965.

It is an object to provide novel graft polymerization processes. Anotherobject is to provide graft polymerization processes free from one ormore of the limitations or disadvantages of prior art graftpolymerization processes. It is another object to provide novelgraftpolymers. Other objects Will be apparent to those skilled in theart towhich this invention pertains.

According to the processes described herein a substantiallyWater-insoluble, syntheic polymeric substrate as defined herein isreacted via peroxidic free radical initiated graft polymerization, withan ethylenic unsaturated monomer to produce a graft polymer.

Mino et al. US. Patent 2,922,768 discloses a process for graftpolymerizing various polymeric materials .using a ceric ion initiatedsystem in which a reducing agent is present. The present graftpolymerizations are peroxidic initiated and utilize polymeric substratesbearing substituents as defined herein which provide the other half ofthe redox system.

British Patent 818,412 discloses a redox graft polymen'zation system inwhich a ferrous, chromous, manganous, etc. ion is bound to the substrateby the ion exchange capacity of the substrate. The present graftpolymerizations utilize sulfur containing substrates as defined hereinto provide, with the peroxidic initiator, the redox system used toeffect the graft polymerization.

There are problems associated with prior art graft polymerizationprocesses, such as the'need'for an inert 3,357,933 Patented Dec. 12,1967 "ice and disadvantages. Moreover,,the graft polymerizations havemany advantages not possessed by other types of graft polymerizations.

The graft polymerizations described herein are novel in that both thesubstrate and monomer participating in the copolymerization may be ofdiverse nature. The substrate may be used in any of its conventionalforms. The copolymerization may be accomplished as a batch process or asa continuous treatment process. Through the proper practice of eachinvention, strength losses can be avoided and a highly efficientaddition of the monomer or monomers to the substrate is accomplished.The properties of the substrate can be modified in virtually any mannerdesired by the choice of monomer or. combination of monomers and theamount thereof grafted to the substrate.

The present graft polymerizations can be carried out in dilute aqueoussolutions of monomer or monomers, as well as in concentrated solutionsof monomer or monomers. Also, each maybe conducted in either dilute orconcentrated suspensions of the substrate.

An inert atmosphere is not essential, but may be used if desired. A verysurprising aspect of the polymerizations is monomer solution need not beentirely free from polymerization inhibitors.

Extremes of temperature are not ordinarily necessary as thecopolymerization will proceed at ambient temperatures.

PEROXIDIC INITIATOR The graft polymerizations described herein utilize aperoxidic initiator as part of the redox system. By redox ide,persulfates such as ammonium, sodium or potasatmosphere, need to operateat either low, high or specsium persulfate, hydroperoxides such ast-butyl hydroperoxide, diisopropylbenzene hydroperoxide, cumenehydroperoxide, 1 phenylethylhydroperoxide, etc., diacylperoxides such asbenzoyl peroxide, acetyl peroxide and the like, di-alkyl peroxides suchas di-tbutyl peroxide, dicumyl peroxide, etc.; peresters such as t-butylperoxyacetate, t-buyl peroxybenzoate andthe like; peracids such asperformic acid, peracetic acid, per'benzoic acid, peroxylactic acid andthe like; and others such as Clialkyl peroxydicarbonates. These peroxycompounds mustbe capable of initiating a free-radical polymerization pbythemselves or in the presence of an activator, such as' a reducingagent. The preferred group of peroxidic freeradical initiators are thosethat are. water-soluble when the copolymerization is conducted in anaqueous medium. As would be expected, the peroxidic initiator should beuniformly distributed throughout the monomer solution.

MONOMERS The monomers which can be co-reacted with the substrate inthemanner described herein to yield new graft polymers are thoseethylenically unsaturated compounds which readily copolymerize orreadily copolymerize with other ethylenically unsaturated compoundseither in bulk, or in an aqueous solution, or as an emulsion, whenexposed-to a-redox system capable of initiating a polymerization orcopolymerization. By the term monor'ner is meant an ethylenicallyunsaturated compound having the structure C=C which encompasses vinylenemonomers of the general form CHR==CHR and vinylidene monomers of thegeneral form H @CR and including the monomers on which all four of theopen valence bonds are occupied by R substituents as well as those inwhich at least two R substituents, one on each carbon atom, form a ringderivative.

The radical R is selected from at least one member of the electro'nac'ce'pting groups and electron-donating groups consisting of:

(1) Hydrogen. I

(2) Al-kyl, alkene; and alkyne, the substituted as well as theunsubstituted in which the hydrocarbon moiety contains less than sixcarbon atoms such as methyl, ethyl, butyl, amyl, heXyl, ethenyl,hydroxymethyl, chloromet'hyl, etc.

(3) Aryl and substituted aryl such as phenyl, alphachlorotolyl, tolyl,4-ch1orophenyl, alpha-tolyl, xylyl, 2- bromo-4 ethylphenyl, etc.

(4) The electronegative groups, e.g., chloro, bromo, cyano, carboxy,carbalkoxy, acyloxyl, alkenyl, and the like.

(5) Alicyclic and heterocyclic,substituted and unsubstituted, such aspyridyl, thienyl, furyl, pyrrolidyl, etc.

(6) Groups of the general formula wherein R is selected from the groupconsisting of hydrogen, R, and substituted as well as the unsubstitutedhydrocarbons containing from 1 to 18 carbon atoms, such as methyl,ethyl, butyl, amyl, hexyl, heptyl, octadecyl, nit'roethyl, riitrobutyl,N,N-di-methylaminoethyl, t-butylaminoethyl, 2-cyanoethyl, c'yclohexyl,N,N-diethylaminoethyl, hydroxyethyl, hydroxypropyl and the like.

(7) Groups of the general formula Rll g (8) Groups of the generalformula R"C-O- (9) Groups of the general formula R"o- (10) Groups of thegeneral formula wherein R" is selected from at least one member of thegroup consisting of hydrogen, R or R, aliphatic groups of from 1 to 18carbon atoms and in addition the substituted as well as theunsubstituted hydrocarbons containing from 1 to 18 carbon atoms such asthe methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octadecyl,chloroethyl, chloromethyl, hydroxyethyl, hydroxypropyl, epoxyet'hyl,phenyl, p-chlorophenyl, and the like.

At least one of the members ofithe following group of ethylenicallyunsaturated monomers which readily homopolymerize' or readilycopolymerize with other ethylenically unsaturated compounds either inbulk, or in an aqueous solution, or as an emulsion may be used:ethylenically unsaturated aromatic compounds and mono, di, tri, tetraand penta substituted aromatic compounds, wherein the ring issubstituted with at least one member selected fromthe class consistingof alkyl (substituted and unsubstituted) having from 1 to 7 carbon atomsand/or with inorganic electron-accepting and/or inorganicelectron-donating groups such as-halogen, nitro, sulfono, etc., andwherein the ethylenically unsaturated moiety has from 2 to carbon atoms,either substituted or unsubstituted such as alpha-methylstyrene,p-chloromethylstyrene, o-methylstyrene, m-methylstyrene,2,4-dimethylstyrene, 2,5 dimethylstyrene, 2,4,5 trimethylstyrene,pethylstyrene, o-bromostyrene, 2-bromo-4-ethylstyrene,p-isopropylstyrene, p-chlorostyrene, 2,4-dichlorostyrene, pbromostyrene, o chlorostyrene, m chlorostyrene, beta-chlorostyrene,2,5-dichlorostyrene, 4-ethoxystyrene, p-isopropyl-alpha-methylstyrene,beta-nitrostyrene, p-nitrostyrene and the like; also polymerizablealkylacrylic acids having from 1 to 5 carbon atoms in the alkyl chainprovided, in all instances, when there is no alkyl chain, thesubstituent is hydrogen or some other specified moiety,'such ashalogens, cyano etc., e.g., acrylic acid, methacrylic acid,alpha-chloroacrylic acid, 2-furfurylacrylic acid and the like;alkylacrylic acid esters having from 1 to 5 carbon atoms in the alkylchain provided, in all instances, when there is no alkyl chain, thesubstituent is hydrogen or some other specified moiety, such as halogen,cyano, etc., and wherein the esters are formed from monohydric alcohols(substituted and unsubstituted) selected from the group consisting ofalkyl alcohols having from 1 to 20 carbon atoms such as amyl acrylate,amyl methacrylate, benzyl methacrylate, benzyl acrylate, glycidylmethacrylate, butyl acrylate, butyl methacrylate, dodecyl acrylate,cyclohexyl acrylate, cyclopentyl methacrylate, ethyl acrylate,methyl-alphabromoacrylate, methyl-alpha-chloroacrylate, ethylmethacrylate, Z-ethylhexyl acrylate, heptyl acrylate,ethylalpha-bromoacrylate, hexyl methacrylate, lauryl methylacry-late,methyl acrylate, methyl methacrylate, stearyl acrylate, stearylmethacrylate, propyl acrylate, 2-bromoethyl acrylate,2-chloroethoxyethyl methacrylate, etc.; the substituted amino alcoholshaving from 2 to 7 carbon atoms in the alkyl chain and from 1 to 7carbon atoms in the alkyl chains on the amino moiety such as N,N-dimethylaminoethyl acrylate, N-t-butylaminoethyl methacrylate,N,N-diethylaminoethyl acrylate, 2-N-morpholinethyl 'methacrylate and thelike; nitro alcohols wherein the alkyl chain has from 2 to 7 carbonatoms such as 3- nitro-2-butanol, 2-nitro-3-hexanol,2-methyl-2-nitro-1-butanol, 2-nitro-2-methyl propanol, etc.; cyanoalkylalcohols wherein the alkyl chain has from 2 to 7 carbon atoms such as2-cyanoethyl acrylate and the like; unsaturated polymerizablealkylacrylic acid amides having from 1 to 5 carbon atoms in the alkylchain provided, in all instances, when there is no alkyl chain, thesubstituent is hydrogen or some other specified moiety described above,and also wherein the amide is formed from ammonia, primary and secondaryamine or a diamine having from 1 to 16 carbon atoms (substituted andunsubstituted) such as acrylamide, methacrylamide, ethacrylamide,methylene-bis-acrylamide, t-butylacrylamide, 2- cyanoacryla-mide,N-(p-chlorophenyl) methacrylamide, N,N-diallylacrylamide,N,N-dimethylacrylamide, hexamethylene-bis-acrylamide,N-alpha-naphthylacrylamide, etc.; 'or the et-hylenically unsaturatednitriles such as acrylonitrile, methacrylonitrile, ethacrylonitrile,alphachloroacrylonitrile and the like; polymerizable alkylene glycol andpolyhydric glycol alkylacrylates and dialkylacrylates having 1 to 5carbon atoms in the alkyl chain provided, in all instances, when thereis no alkyl chain, the substituent is hydrogen or some other specifiedmoiety described above, such as ethylene glycol dimethacrylate,triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate,tetramethylene di-methacrylate, glyceryl triacrylate, hydroxyethylmethacrylate, hydroxypropyl methacrylate and the like; fatty acid estersof 1- olefins (substituted and unsubstituted), containing from. 2 to 24carbon atoms but preferably from 2 to 18 atomsv wherein the l-olefinalcohol precursor of the fatty acid esters has from 2 to 8 carbon atomsbut preferably 2 to 3 carbon atoms, such as, vinyl acetate, vinylpropionate, vinyl butyrate, isopropenylacetate, vinyl-n-hexanoate,vinylchloroacetate, vinylcrotonate, vinyl-n-decanoate, vinyl-formate,vinyl-2-ethyl hexoate, viny-l laurate, vinyl oleate, vinyl stearate,vinyl trifluoroacetate, allyl linolate, allyl oleate, allyl acetate,allyl propionate, allyl chloroacetate, allyl caproate, allyl butyrate,etc.; aromatic acid esters (substituted and unsubstituted) ofunsaturated alcohols wherein the alcohol precursor has from 2 to 8carbon atoms but preferably from 2 to 3 carbon atoms such as allylbenzoate, diallyl'phthalate, vinyl phthalate, vinyl benzoate, etc.;ethylenically unsaturated aliphatic diacids containing from 4 to 10carbon atoms but preferably from 4 to 6 carbon atoms, and their esters,nitriles and amides such as, itaconic acid, maleic acid, fumaric acid,dimethyl maleate, dibutyl maleate, dimethyl fumarate, dibutyl fumarate,maleic anhydride, diethyl furnarate, etc.; polymerizable aliphaticdienes such as butadiene, 2,3-dimethyl butadiene, isoproprene,pentadiene, etc. and the haloprenes such as chloroprene and the like;l-olefins (substituted and unsubstituted) containing from 2 to 18 carbonatoms but preferably from 2 to 8 carbon atoms such as vinyl chloride,vinylidene chloride, allylamine, diallylamine, diallylphosphate, allylchloride, nitroethylene, 'butadiene monoxide, vinyl acrylate and thelike; the vinyl ethers (substituted and unsubstituted), such asvinylethyl ether, vinylpropyl ether, vinylisobutyl ether,vinyl-Z-methoxyethyl ether, vinyl-n-butyl ether, vinyl 2-chloroethylether, vinyl-2-ethylhexyl ether and the like or other vinyl compoundssuch as divinylsulfone, divinylsulfide, divinylbenzene, etc.;ethylenically unsaturated heterocyclic compounds wherein the heterocyclecontains from 3 to 5 carbon atoms and the hetero atoms are selected fromthe group consisting of N, O and S such as the vinyl pyridines, N-vinylpyrrolidone, vinyl furan, alpha vinyl thiophene and the like. Ingeneral, the only requirement necessary in order for a monomer to beuseful in this invention is that it has at least one olefinic doublebond which readily homopolymerizes or readily copolymerizes with otherethylenically unsaturated compounds eit-her in bulk, or in an aqueoussolution, or as an emulsion.

More specifically, at least one member of the following group ofpolymerizable or copolymerizable monomers is useful; styrene,p-chloromethyl styrene, sodium p-styrene-sulfonate, vinyl toluene,2,5-dichlorostyrene, alpha-methyl styrene, acrylamide, acrylic acid,acrylonitrile, N-t-butyl acrylamide, methacrylamide,N,N-methylene-bis-acrylamide, N,N-diethylacrylamide, methacrylic acid,t-butylaminoethyl methacrylate, N,N-diethylaminoethyl acrylate,N,l\l-diethylarninoet-hyl methacrylate, N, N-dimethylaminoethylacrylate, Z-cyanoethyl acrylate, n-butyl acrylate, n-butyl methacrylate,decyl acrylate, decyl 'methacrylate, ethyl acrylate, Z-ethylhexylacrylate, ethyl methacrylate, glycidyl acrylate, glycidyl methacrylate,n-hcxyl methacrylate, n-lauryl Inet-hacrylate, methyl acrylate, methylmethacrylate, decyl-octyl meth acrylate, stearyl methacrylate, ethyleneglycol dimethacrylate, triethylene glycol dimethacrylate, tetraethyleneglycol dimethacrylate, polyethylene glycol dimethacrylate, hydroxypropylmethacrylate, hydroxyethyl methacrylate, diallyl adipate, diallylmaleate, N,Nadiallyl melamine, diallyl phthalate, .diallyl phosphite,diallyl phosphate, diallyl fumarate, vinyl chloride, vinylidenechloride, maleic acid, itaconic acid, fumaric acid, di-nbutyl fumarate,di-n-butyl maleate, di-n-butyl itaconate, diethyl maleate, methyl vinylketone, Z-methyl-S-vinylpyridine, N-vinyl carbazole, 2-vinyl pyridine,1-vinyl-2- pyrrolidone, N-viny-l pyrrolidone, vinyl-n-butyl ether,vinyl-isobutyl ether, vinyl-Z-chloroethyl ether, vinyl ethyl ether,vinyl-2-ethylhexyl ether, vinyl triethoxysilane, vinyl stearate, vinylbutyrate, vinyl acetate, vinyl-2-ethyl-hexoate, viny-l propionate,divinyl benzene and divinyl sulfone.

SUBSTRATES The water-insoluble substrates utilized. in the graftpolymerization processes described herein are thioated syntheticpolymers containing hydroxyl groups or groups hydrolyzable thereto,including thioated cellulose ethers and esters.

The term substantially water-insoluble means a substrate whosesolubility, in the form in which it is employed, in water at 30 C. orless does not exceed about percent of its weight. Because the substrateused in the graft polymerizations described herein is usually formedunder alkaline conditions, both it and the polymeric substance fromwhich it is formed must also be substantially alkaline insoluble,atleast at the alkaline pH used to form the 6 substrate and to graftpolymerize, if alkaline conditions are employed.

The thioated substrates are, except as otherwise stated herein,dithiocarbonate derivatives and monothiocarbonate derivatives of theparent polymer. These thioated substrates can be produced by thereaction of the alkaline wet parent polymer with carbon disulfide andcarbonylsulfide, respectively.

The term synthetic polymers containing hydroxyl groups or groupshydrolyzable to hydroxyl groups means polymers capable of forming athioate (dithioate or monothioate) derivative in the presence of a base.For example, esters of hydroxyl polymer having no free hydroxy groupsbut which are at least slightly hydrolyzed in the presence of a base sothat a thioate derivative may be produced therefrom are included withinthe term. Examples of such polymers are polyvinyl alcohol, partiallysaponified polyvinyl acetate, polyvinyl acetate, copolymers of polyvinylalcohol and copolymers of polyvinyl acetate, copolymers of vinylacetate, e.g., copolymers of vinyl acetate and styrene, vinyl acetateand ethylene, vinyl acetate and vinyltoluene, vinyl acetate andisoprene, vinyl acetate and divinylsulfone, vinyl acetate and vinylidinechloride, and the like, as well as the hydrolysis products of copolymersof these types, and polymers and copolymers of hydroxyethylacrylate,e.g., hydroxyethylacrylate, copolymers of hydroxyethylacrylate andtyrene, hydroxyethylacrylate and isoprene, hydroxyethylacrylate andacrylonitrile, hydroxyethylacrylate and ethylacrylate, etc., andpolymers and copolymers of hydroxyethylmethacrylate, e.g., poly(hydroxyethylmethacrylate), copolymers of hydroxyethylmethacrylate andvinyltoluene, hydroxyethylmethacrylate and butadiene,hydroxyethylmethacrylate and vinylpyridine, etc., and polymers andcopolymers of hydroxypropylacrylate and hydroxypropylmethac-rylate,e.g., poly (hydroxypropylacrylate), poly (hydroxypropylmethacrylate),copolymers of hydroxypropylmethacrylate and butylacrylate,hydroxypropylacrylate and vinylidine chloride, hydroxypropylmethacrylateand isoprene, etc., can be used to produce the thioate-d substrate.

Included in this broadly defined class of synthetic polymers are ethersand esters of cellulose, i.e., derivatives of cellulose in which aportion of the hydroxy groups of cellulose has been etherified oresterified, e.g., cellulose monoacetate, cellulose diacetate, cellulosetriacetate, cellulose propio'nate,' cellulose acetate propionate,cellulose acetate butylate, nitrocellulose, methyl cellulose, ethylcellulose, hydroxyethyl cellulose, propyl cellulose, butylcellulose,carboxymethylcellulose, the degree of substitution being such that athioated derivative can be produced which is substantially waterinsoluble. These synthetic polymers can be used in their conventionalforms, i.e., as powders or in the form of sheets, films, fi-bers,filaments, woven cloth, knitted fabrics, garments, etc. I

DESCRIPTION OF PROCESS A. THIOATED SUBSTRATE FORMATION The term thioatedsubstrate embraces dithiocarbonated and monothiocarbonated substratesand the corresponding substrates produced by disproportionation orrearrangement during mono-, or di-thiocarbonation.

The thioated substrate which is graft polymerized can be prepared bywetting the corresponding non-thioated substrate with an alkalinesolution. This is done, generally, with a sodium hydroxide solution, ora solution of some other alkali metal hydroxide. The strength of thealkaline solution used in each particular case will be dependent, ofcourse, upon the nature of the substrate and the type of end-productdesired; but generally, concentrations in the range of about .05 molarto'about 1 molar are preferred. The amount of alkali or alkaline'salt ormixture of alkalies and alkaline salts used is that'amount necessary toachieve the desired degree of thiocarbonation of the substrate. Unless avery high or very low degree of thioation is desired, the amount ofalkali employed is not particularly critical so long as it does notresult in the production of a water soluble thioate. Such alkalies aslithium, sodium, potassium, rubidium, and cesium hydroxides, ammoniumhydroxide, quaternary ammonium hydroxides such as tetramethylammoniurnhydroxide, rnethyltriethylammonium hydroxide, trimethylbenzylammoniumhydroxide and the like, quaternary phosphonium hydroxides such astetraethylphosphonium hydroxide, trimethylphen ylphosphonium hydroxide,methyltriethylphosphonium hydroxide, trimethylisoamylphosphoniumhydroxide, and the like, sulfonium hydroxides such as triethylsulfoniumhydroxide, methyldiethylsulfonium hydroxide, dimethylbenzylsulfoniumhydroxide, methyldiethylsulfonium hydroxide and the like, quaternaryarsonium hydroxides such as trirnethylphenylarsonium hydroxide,tetraethylarsonium hydroxide methyltriphenylarsonium hydroxide and thelike, and quaternary stibonium hydroxides such as tetramethylstiboniumhydroxide, tetraethylstibonium hydroxide, methyltriethylstiboniumhydroxide and the like, as well as the slightly soluble alkaline earthmetal hydroxides such as calcium, strontium, barium, etc. may be used,although the preferred method of preparation of the alkaline earth metalsubstrate thiocarbonate salts is from the alkali metal substratethiocarbonate salts by metathesis. An alkali metal substratethiocarbonate salt may also be converted to a quaternary ammonium,sulfonium, quaternary phosphonium, quaternary arsonium or quaternarystilbonium substrate thiocarbonate through metathesis.

In addition to the strong and relatively strong bases mentioned above,basic salts, and water soluble organic amines serve equally well. Suchbasic salts, or mixtures of these salts as sodium carbonate, trisodiumphosphate, disodium hydrogen phosphate, disodium ammonium phosphate,sodium silicate, sodium aluminate, sodium antimoniate, sodium stannate,sodium cyanide, sodium cyanate, sodium sulfide, potassium carbonate,tripotassium phosphate, dipotassium phosphate, potassium silicate,ptassium aluminate, potassium antimoniate, potassium stannate, potassiumcyanide, potassium cyanate, potassium sulfide, lithium carbonate,trilithium phosphate, dilithium hydrogen phosphate, lithium silicate.and the like, as well as such Water-soluble amines as methylamine,ethylamine, dimethylamine, pyridine, and such quaternary ammoniumhydroxides as tetramethylammonium hydroxide and benzyltrimethylammoniumhydroxide are just a few examples of basic materials which have servedequally well in the preparation of the various water-insolublethiocarbonates. In fact, a basic salt whose aqueous solution has a pH ofabout 8 or 9 or greater maybe suitable. It should be recognized, also,that a mixture consisting of a basic salt and an inorganic or organichydroxide is included in this group. However, those basic salts whichare known to chemically modify the substrate and which would therebyinterfere with the thiocarbonation process are to be avoided whenpracticing this invention.

Thiocarbonation can be accomplished by bringing the alkaline-wetsubstrate into intimate contact with carbon disulfide or carbonylsulfide. Either vaporous carbon disulfide or carbonyl sulfide or asolution of the sulfide in any inert solvent or an aqueous emulsion ofthe sulfide in an inert water immiscible organic solvent may be used.The thiocarbonation reaction is conducted as long as is necessary toacquire the desired degree of thiocarbonation. Usually merely exposingthe alkaline substrate to the carbonyl sulfide or carbon disulfidesufiices.

Thiocarbonation is of a relatively low order, i.e., substrates areproduced having thioate sulfur contents of the order of 0.5 percent andusually 0.3 percent or less. This low thiocarbonation is, of course,vital when it is possible to produce a water-soluble thioated substrate.

The techniques known in the art can be used to produce water insolublethioated substrates, e.g., using carbon disulfide in the presence ofalkali to produce a dithiocarbonated substrate and carbonyl sulfide inthe presence of alkali to produce a monothiocarbonated substrate.

A wide variety of thiocarbonate salts can be produced by reacting, bymetathesis, an ammonium, organic ammonium, phosphonium, sulfonium,arsonium, sti-bonium salt or an alkali metal salt such as lithium,sodium, potassium, etc. of the thiocarbonate of the substrate with awater-soluble salt of a metal or mixture of metals from Group lb of thePeriodic Table such as Cu, Ag, and Au; Groups 11a and III; such as Mg,Ca, Sr, Zn, Cd, etc.; Groups 111a and 1111; such as Sc, Y, La, Al, Ga,etc. Group IV!) such as Ti, Zr, etc., as well as Ge, Sn and Pb; Group Vbsuch as V, Nb, etc.; as well as Bi; Group VIb such as Cr, W, etc.; GroupVIIb such as Mn, etc.; and Group VIII such as Fe, Co, Ni, Os, etc., toyield a new thiocarbonate derivative of the metal.

In general, the previously described alkali metal salts of thethiocarbonate are used if copolymerization is to be carried out withoutundue delay. At times, however, it is advantageous to effect aconversion of the alkali metal thiocarbonate salt to a salt which ismore stable, or which is a more reactive intermediate. For example,aluminum thiocarbonate of the substrate is prepared by passing analuminum sulfate or aluminum acetate solution through, about, or over analkali metal thiocarbonate of the polymeric substrate. The zincthiocarbonate of the substrate is prepared from zinc chloride or someother soluble zinc salt, zirconyl thiocarbonate from Zirconiumoxychloride, uranyl thiocarbonate from uranyl acetate, leadthiocarbonate from lead acetate, and ferrous thiocarbonate from ferrousammonium sulfate or ferrous chloride, etc. This technique is especiallyuseful when a soluble hydroxide or basic salt of the desired cation isnon-existent or unavailable.

The thioated substrate, when graft polymerized with the monomer, must besubstantially free from any Watersoluble byproducts of the thioateformation or thioate substrate decomposition, i.e., decomposition ofthioate groups, which are known in the art to be labile. Thus, after itsformation the thioated substrate, in the form of an alkali metal salt,alkaline earth metal salt, or an ammonium salt, or the previouslydescribed converted metal salts, is washed with water to removewater-soluble reaction by-products and free metal ions, preferablyimmediately prior to its suspension in an emulsion or solution of thepolymerizable ethylenically unsaturated monomer to ensure no furtherformation of by-products prior to polymerization.

The structures of the thioated substrates are not certain. However, inthe case of the monothiocar-bonate derivatives, they are believed tohave the formula or its disproportionated or rearranged moiety, e.g.,

S O a in which R is the polymer substrate and Y is hydrogen or a saltderivative of the acid. Similarly, in the case of the dithiocarbonates,they are believed to have the formula or its disproportionated orrearranged moiety, e.g.,

wherein R and Y have the values given above.

B. POLYMERIZATION Graft polymerization is accomplished by reacting thethioate derivative of the substrate, either as a salt or thecorresponding free acid obtained by converting an ammonium, organicammonium, sulfonium, phosphonium, arsonium, stibonium, or an alkalimetal salt of the thiocarbonate derivative to the free thiocarbonic acidderivative, with an ethylenically unsaturated monomer or monomers fromone of the groups set out above in the presence of a peroxidic freeradical initiator.

The copolymerization reaction is conducted in either an aqueous ornonaqueous system, but preferably and ordinarily in an aqueous system,in which the monomer is uniformly distributed. When the reaction mediumis aqueous, a solution, suspension, or an emulsion of the ethylenicallyunsaturated monomer can be used to achieve uniform distribution of themonomer. The presence of a wetting agent in the reaction medium isadvantageous since it facilitates monomer penetration into the thioatesubstrate. Emulsifiers can be used to achieve a uniform emulsion of aninsoluble monomer and/or peroxidic initiator.

The selected thiocarbonate salt or free acid can be used in virtuallyany proportion to the monomer, e.g., from about 0.5 percent to 99.9percent by weight based on the ethylenically unsaturated monomer. Themonomer can also be used in almost any concentration in the solution,e.g., from about 1 percent to about 100 percent of the total reactionsolution. The solution can be buffered, if necessary, or its pH adjustedto provide the best polymerization conditions for the selected monomers.After adding a water soluble peroxidic free-radical initiator to thesolution containing the substrate and monomer, the reaction will proceedat virtually any temperature, e.g., from about to about 100 C. Reactiontimes can vary from 3 minutes to about 96 hours or longer and reactionpressure can be atmospheric, subatmospheric or superatmospheric,depending upon the monomer and the type of product desired. The thioatedsubstrate can also be added to a mixture of the monomer and peroxidicinitiator in the selected reaction media. The usual graft polymerizationtechniques employing a peroxidic initiated system can be used. However,because of the ease of graft polymerization, less rigorous conditionsare ordinarily required. For example, mildly acidic aqueous conditionsat room temperature are sufiicient to achieve any degree of monomeradd-on desired, e.-g., from 5 percent to 500 percent.

As is well known in the art, the properties of the graft polymerproduced depends upon the substrate used, the monomer or mixture ofmonomers used, the percent of add-0n of monomer achieved, and thereaction conditions employed.

The graft polymer can, if desired, be purified using conventionaltechniques, e.g., to remove sulfur containing products, monomer,homopolymer, alkali, etc.

In the practice of this invention, it is possible to design the finalmacromolecular products so that they have a wide range of properties bycontrolling the extent or degree to which thiocarbonate groups have beenadded to the synthetic, polymeric substrate. For example, it is possibleto introduce a few thiocarbonate groups per polymer molecule by merelyreacting a very small percentage of the'reactive sites present in thepolymeric substrate with carbonyl sulfide or carbon disulfide; on theother hand, all or nearly all of the reactive sites may be converted tothiocarbonate groups. It is preferred, however, that the degree ofthiocarbonation be such that there is no apparent outward change in thephysical form of the thiocarbonated derivative, nor that thethiocarbonate derivative becomes soluble in water. Also, all orsubstantially all water-soluble by-products arising from thethiocarbonation reaction ought to be removed prior to thecopolymerization, e.g., by washing. The thiocarbonate substrate may beused in the subsequent polymerization step either as the half ester ofthiocarbonic acid, or as a salt of the half ester of thiocarbonic acid.The salt may be that of any of the metallic elements of the PeriodicTable as well as ammonia. In addition, the salt may be that of anorganic species which possess a positive charge, such as the organicammonium, phosphonium, sulfonium, arsonium and stibonium groups. Themetal ions may be monovalent or multivalent, and if the metal ion is ina lower valence state, e.g., Fe++, it makes an excellent contribution tothe redox system.

Because the thioate groups of the substrate are unstable, it ispreferred that the graft polymerization process be part of a multiplestep process comprising (a) forming the thioated substrate, b) washingthe substrate with water to remove the water-soluble by-products of thethioate step, and (c) mixing the freshly Washed thioated substrate withthe monomer-peroxidic initiator solution to initiate polymerization.Homopolymer formation can sometimes be significantly reduced byemploying these steps as part of an uninterrupted sequence, at least thewashing and polymerization steps.

GRAFT POLYMERIZATION 0F HYDROXYL-GROUP CONTAINING iSY NTHETIC SUBSTRATESBecause many synthetic polymers containing hydroxyl group or groupshydrolyzable thereto are decomposed or solubilized by alkali, care mustbe taken when producing their thioated derivatives to avoid such adversealteration of the substrate. It is to be understood that if thesubstrate contains only groups hydrolyzable to hydroxyl groups, somechemical modification of the substrate by the alkali used appearsnecessary in order to form the thioate groups. However, this involves aminimum of modification and need not, and preferably does not involve asubstantial change in the hydroxyl number or depolymerization.Ordinarily, wetting of the polymer with alkali at or below ambienttemperature is all that is required. The choice of alkali and itsstrength will, of course, depend upon the sensitivity of the selectedpolymer to the base. Sodium hydroxide concentrations of about 0.05 toone molar are preferred.

In order to describe the present invention so that it may be moreclearly understood, the following examples are set forth in which allparts are expressed in parts by weight unless otherwise stated. Theseexamples are set forth primarily for the purpose of illustration, andany specific enumeration of detail contained should not be interpretedas a limitation on the concept of this invention.

Example 1a Five parts of polyvinyl alcohol (Air Reduction ChemicalCompany, KR-30) were placed in a beaker containing enough 0.063 M sodiumhydroxide solution'to cover it completely for 4 hour and then filteredon a Biichner funnel. The resultant alkaline-wet polvinyl alcohol wasthen placed in an evacuated vacuum desiccator over carbon 'disulfide forabout 2%. hours in order to form a dithiocarbonate derivative of thepolyvinyl alcohol. This dithiocarbonated polyvinyl alcohol was firstsuspended in about 100 parts of water, filtered on a Biichner funnel,and washed on the Biichner funnel with water (300-400 parts) in order toremove all soluble by-products which had formed during thedithiocarbonation process. After washing, the moistdithiocarbonatedpolyvinyl alcohol was suspended in a previouslypreparedemulsion consisting of 4.0 parts acrylonitrile, 45 parts water,0.2 part Tween- (a polyoxyethylene sorbitantrioleate), and 1.5 parts of30% hydrogen peroxide. After standing at room temperature (25 27 C.) for18 hours, the copolyme-rized polyvinyl alcohol was removed from thepolymerization 'mixture and thoroughly washed with water. The product,oven dried, weighed 7.54 parts which constitutes a 83.7% yield of :thetheoretical. Prolonged extraction of this material 1 1 withdimethylforrnamide indicated that 91.3% of the monomer which had beenconverted to polymer was nonextractable.

Example 2a Five parts of polyvinyl alcohol were dithiocarbonated in themanner described in Example 1a, above. The dithiocarbonated polyvinylalcohol was then washed thoroughly on a Biichner funnel with water toremove soluble byproducts and then 100 parts of 0.06 M lead acetatesolution were passed over and through the polyvinyl alcohol derivativeto form lead polyvinyl alcohol dithiocarbonate by metathesis. The leadproduct, after washing with sufficient water (150-200 parts) to removeexcess lead ions, was added to an emulsion prepared from 3.75 partsstyrene, 0.25 parts acrylonitrile, 45 parts of distilled water, 0.5 partof Tween-85 and 1.5 parts of 30% hydrogen peroxide. After 18 hourscontact at room temperature with this emulsion, the polyvinyl alcoholcopolymer was washed well with water and dried. The yield of copolymeramounted to 7.55 parts which constitutes an 83.0% yield of thetheoretical. Prolonged extraction with trichloroet-hane showed that 70%of the monomer which had been converted to copolymer could not beremoved.

Examples 312-811 Five parts of polyvinyl alcohol were dit-hiocarbonatedand converted to various polyvinyl alcohol dithiocarbonate salts bymetathesis in the manner described in Example 2a. Each dithiocarbonatederivative was suspended for 18 hours in a polymerization mixture asthat described in Example 1a before being process for yields. Some ofthe results, representative of the various polyvinyl alcoholdithiocarbonate salts used, are tabulated below:

Example 9a Five parts of polyvinyl alcohol were dithiocarbonated in themanner described in Example 1a and the resultant sodium polyvinylalcohol dithiocarbonate was converted by metathesis to aluminumpolyvinyl alcohol dithiocarbonate by substituting 0.06 M aluminumacetate for 0.06 M lead acetate as illustrated in Example 2a, andsuspended in an emulsion consisting of 5.0 parts acryl-amide, 50 partswater, and 1.5 parts of 30% hydrogen peroxide. After 18 hours at roomtemperature (25 27 C.), the product was washed thoroughly with warmwater and dried. The yield of copolymer amounted to 6.2 parts whichconstitutes a 24% conversion of monomer to unextractable polymer.

Example 10a Five parts of polyvinyl alcohol were dithiocarbonated asdescribed in Example 1a and the resultant sodium dithiocarbonate ofpolyvinyl alcohol converted to the zinc salt with 0.06 M zinc acetate bymetathesis. The Zinc derivative was suspended in an emulsion preparedfrom 4.5 parts ethyl acrylate, 45 parts water, 0.2 part Tween 85 and 1.5parts of 30% hydrogen peroxide. After 18 hours at room temperature, thepolyvinyl alcohol copolymer was Washed with water and dried. Thecopolymeric product amounted to 7.73 parts which constitutes an 12 81.5%yield of the theoretical. Prolonged extraction of the product withacetone indicated that 60.2% of the monomer which had been converted topolymer could not be extracted.

Example 11a Five parts of polyvinyl alcohol were placed in a beakercontaining suflicient 0.25 M sodium silicate solution to cover itcompletely. This mixture was allowed to remain at room temperature forabout 1% hours then filtered on a Biichner funnel to remove excesssilicate solution. The sodium silicate Wetted polyvinyl alcohol was thenplaced in an evacuated vacuum desiccator over carbon disulfide for about1% hours before Washing the product in water and filtering on aBi'lchner funnel. Immediately after washing, the dithiocarbonatedpolyvinyl alcohol was converted from the sodium salt to the aluminumsalt by methathesis with aluminum acetate as in Example 9a and suspendedin an emulsion containing 4.0 parts acrylonitrile, 45 parts water, 0.2part Tweenand 1.5 parts 30% hydrogen peroxide. After 18 hours in thereaction medium, the polyvinyl alcohol copolymer was washed thoroughlywith water, yielding a dried product which amounted to (6.88 parts)76.5% of the theoretical yield. Prolonged extraction of this copolymerwith dimethyl fo-rmamide indicated that 72% of the monomer which hadbeen converted to polymer could not be extracted.

Example 12a Five parts of polyvinyl alcohol were sodium dithiocarbonatedas described in Example 11a and immediately thereafter converted to thelead salt as described in EX- ample 2a. The lead polyvinyl alcoholdithiocarbonate was added to an emulsion consisting of 4.5 parts ofethyl acrylate, 45 parts water, 0.2 part Tween-85 and 1.5 parts of 30%hydrogen peroxide. After 18 hours at room temperature the polyvinylalcohol copolymer was washed well with water and dried. The yield ofcopolymer amounted to 82.3% (7.8 parts) of the theoretical of which71.2% of the monomer which had been converted to polymer wasnon-extractable with acetone.

Example 13a Five parts of polyvinyl alcohol were dithiocarbonated asdescribed in Example 11a. This sodium dithiocarbonated PVA was thenconverted by metathesis to ferrous polyvinyl alcohol dithiocarbonate bysubstituting 0.06 M ferrous ammonium sulfate for 0.06 M lead acetate, asdescribed in Example 2a, and then suspended in a solution consisting of5.0 parts acrylarnide, 45 parts of water, and 1.5 parts of 30% hydrogenperoxide. Upon standing at room temperature for 18 hours, the polyvinylalcohol copolymer was removed from the polymerization mixture andthoroughly washed with water. The dried product weighed 6.3 parts whichconstitutes a 25.4% conversion of monomer to unextractable polymer.

Example 14a Five parts of polyvinyl alcohol were placed in a beaker withenough 5% ammonium hydroxide to cover it completely. After about /4hour, the polyvinyl alcohol was filtered free of excess ammoniumhydroxide solution on a Biichner funnel and then placed in a vacuumdesiccator containing carbon disulfide for 3 hours. The resultantproduct was suspended in about parts of water and followed by filtrationon to a Biichner funnel. After further washing with water on theBiichner funnel, the dithiocarbonated polyvinyl alcohol was suspended inan emulsion consisting of 3.75 parts of styrene, 0.25 partacrylonitrile, 45 parts water, 0.5 part Tween85, and 1.5 parts 30%hydrogen peroxide, which had been adjusted to about pH 3.0 with dilutehydrochloric acid. After 18 hours in this emulsion, the copolymerizedpolyvinyl alcohol was Washed thoroughly with Water. The dried productamounted to 67.8% (6.1 parts) of the theoretical yield and 63.2% of 13the monomer which had been converted to polymer could not be extractedwith trichloroethane.

Example 15a Five parts of polyvinyl alcohol were placed in a beaker andenough 0.25 M sodium carbonate was added to cover the polyvinyl alcohol.The mixture was allowed to stand at room temperature for about /2 hourand then filtered on a Biichner funnel.

This alkaline-wet polyvinyl alcohol was next placed in an evacuatedvacuum desiccator over carbon disulfide. After about 4 hours, thedithiocarbonated polyvinyl alcohol was suspended in about 100 parts ofwater, filtered on a Biichner funnel, Washed with water (150-200 parts)and immediately converted to the zinc salt by metathesis, as describedin Example 10a, and then suspended in an emulsion consisting of 3.75parts of styrene, 0.25 part of acrylonitrile, 45 parts of Water, 0.5part of Tween- 85 and 1.5 parts of 30% hydrogen peroxide. After 18hours, the copolymerized polyvinyl alcohol was washed with water anddried. The product yield amounted to 6.95 parts which constitutes 76.5%yield of the theoretical. Prolonged extraction in trichloroethaneindicated that 52.4% of the monomer which had been converted to polymercould not be extracted.

Example 16a Five parts polyvinyl alcohol were placed in a beaker andenough 4% triethylamine solution was added to cover the polyvinylalcohol. This mixture was allowed to stand at room temperature for abouthour, filtered and dithiocarbonated for hours as described in Example150. The dithiocarbonated polyvinyl alcohol was suspended in about 100parts of water, filtered on a Biichner funnel and thoroughly washed withwater (150-200 parts). The resultant product was next dispersed in anemulsion prepared. from 4.0 parts of acrylonitrile, 45 parts of water,0.2 part of Tween-85 and 1.5 parts of 30% hydrogen peroxide. Thepolymerization mixture was then adjusted to a pH of about 3.0 withhydrochloric acid. Upon standing at room temperature for 18 hours, thecopolymerized polyvinyl alcohol was removed from .the polymerizationmixture and thoroughly washed'with water. The 'dried product weighed7.42 parts which constitutes an 82.5% yield of the theoretical.Prolonged extraction in dimethylforrnamide indicated that 80% of themonomer which had been converted to polymer could not be extracted.

Example 170 ,Five parts. of polyvinyl alcohol (du Ponts Elvanol 7260)were placed in a beaker and enough sodium bicarbonate (saturated)solutionwas. added to cover the polyvinyl alcohol. The mixture wasallowed to stand at room temperature for about hour and then filtered ona Biichner funnel. The alkaline-wet polyvinyl alcohol was-placed in anevacuated vacuum desiccator over carbon dis-ulfide for about 21h0urs,",after which the dithiocarbonated polyvinyl alcohol was suspendedin about 100 the, monomer which had been converted to polymer could notbe extracted.

14 Examples 18a-21a Five parts of polyvinyl alcohol were placed in abeaker containing sufficient 0.25 M sodium. aluminate solution to coverit completely for hour and then dithiocarbonated as described in Example150. The sodium dithiocarbonate salt was suspended in each of thefollowing polymerization media:

Ex- Percent Percent nona 'n- Monomer Procedure yield extractable plepolymer 181..- Ethyl acrylate Example 10a. 70 67 191,..- AerylamideExample 9a. 66 100 20 1.... Acryloditrile Example 1a 70 83 21a...Styrenelacryloultrile.. Example 8a 70 51 Example 22a Ten parts ofhydroxyethyl cellulose (Rayonier,

Example 23a Ten parts of ethyl cellulose (Hercules N-lO -S) weresuspended in a dispersion of 2 parts carbon disulfide with 98 parts0.25% sodium hydroxide solution. After about 2 hours, the mixture wasfiltered on a Biichner funnel and washed with-water (350-400 parts) inorder to remove completely all soluble products which-had formed duringthe dithiocarbonation process. After the water wash, thedithiocarbonated ethyl cellulose Was dispersed in an emulsion consistingof 8.0 parts acrylonitrile, 40 parts water, 0.4 part Tween-85 and 2.5parts 30% hydrogen peroxide. After 18 hours, the copoly-merized ethylcellulose was washed well with water and dried. The final productweighed 13.7 parts which constitutes a 76% yield of the theoretical.

Example 24a Ten parts of cellulose acetate staple were placed in abeaker containing 200 parts of 0.75 M sodium hydroxide solution forabout hour and dithioca-rbonated as described in Example 1a. Thedithiocarbonated derivative was then suspended in an emulsion preparedfrom 8.0 parts acrylonitrile, parts water, 0.4 part Tween-85 and 3.0parts of 30% hydrogen peroxide. After 20 hours, the copoly-merizedsubstrate was Washed well with water and dried. The product weighed 10.3parts and was found to contain 16.6% nitrogen which indicates an 81.5%conversion of monomer to polymer (6.5 parts polyacrylonitrile).

Extraction of this product with dimethylform-amide showed that 72% ofthe monomer which had been converted to polymer could not be extracted.

Example 25a 1 5 yield of the theoretical. Prolonged extraction indimethylformamide indicated that 72.5% of the monomer which had beenconverted to polymer could not be extracted.

Examples 26a-31zz A number of S-part samples of polyvinyl alcohol wereprepared and reacted as described in Example la with the exception thatthe aerylonitrile was replaced with other monomers. The results of thesesubstitutions are listed below:

Percent Wt. of Conversion of Percent Ex Monomers monomer monomer tononexused (gr.) polymers on tractable substrate polymers 26a. n-Butylacrylate 4. 5 71 69 27a Glycidyl acrylate 5. 83 28a Methacrylamide' 5. 068 100 29a. Methyl methaerylate 5. 0 79 71 30a- Hydroxypropyl meth 4. 7565 aerylate. 31a Viuylidene chloride 5. 0 67 61 Tween-85 was omitted inthis reaction.

Example 3241-3 7a A series of S-part samples of polyvinyl alcohol wereprepared and treated as described in Example 5a. Ferration wasaccomplished by suspending the dithiocarbonated substrate for about 1minute in a 0.004% aqueous ferrous ammonium sulfate solution.Copolymerization was effected with a variety of monomers in place ofacrylonitrile. The results were as follows:

Tween-85 was omitted in this reaction.

(Example 1 b Ten parts of polyvinyl alcohol (du Ponts Elvanol 72- 60)were placed in a beaker containing enough 0.063 M sodium hydroxidesolution to cover it completely for hour and then filtered on a Biichnerfunnel. This alkaline-wet alcohol was then placed in a gas drying tower,the outlet of which led to a mercury reservoir so that a slight gaspressure could be maintained within the drying tower. The inlet part ofthe drying tower was connected to a cylinder of carbonyl sulfide andsufficient carbonyl sulfide was flushed through the system to displacethe air and to maintain a slight pressure to the atmosphere of carbonylsulfide remaining over the alkaline-Wet polyvinyl alcohol. After about20 minutes exposure time to the carbonyl sulfide, the polyvinyl alcoholmonothiocarbonate was suspended and mixed in about 100 parts of water,filtered on a Biichner funnel, and washed on the Biichner funnel withwater (300-400 parts) in order to remove all soluble by-products whichhad formed during the monothiocanbonationprocess. After washing, the

moist monothiocai bonated polyvinyl alcohol was dispersed in apreviouslyprepared emulsion consisting of 8.1 parts ,acrylonitrile, 50parts water, 1.0 part Tween-85 (a polyoxyethylene sorbitantrioleate),and 3.0 parts of 30% hydrogen peroxide and adjusted to a pH of about 5.0with hydrochloric acid. After standing at room temperature 2'2-25 C.)for 18 hours the polyvinyl alcohol copolymer was removed from thepolymerization mixture and thoroughly washed with water. The product,

16 oven dried, weighed 14.10 parts, which constitutes a 78.2% yield ofthe theoretical. Prolonged extraction of this material withdimethylformamide indicated that 75.7% of the monomer which had beenconverted to polymer was nonextractable.

Exdmple 2b Ten parts of polyvinyl alcohol were monothiocarbonated in themanner described in Example lb. Immediately after washing, themonothiocarbonated polyvinyl alcohol was suspended in an emulsionprepared from 9.25 parts ethyl acrylate, 50' parts water, 1.0 partTweenand 3.0 parts of 30% hydrogen peroxide and adjusted to a pH ofabout 5.0 with 10% hydrochloric acid. After 18 hours contact at roomtemperature with this emulsion, the polyvinyl alcohol copolymer waswashed well with water and dried. The yield of copolymer amounted to15.8 parts which constitutes an 82.0% yield of the theoretical.Prolonged extraction in acetone showed that 80.1% of the monomer whichhad been converted to copolymer could-not be removed.

Example 3b Ten parts of polyvinyl alcohol were monothiocarbonated andWashed in the manner described in Example 1b, and dispersed in asolution consisting of 10.0 parts acrylamide, 50 parts water and 3.0parts 30% hydrogen peroxide and adjusted to a pH of about 5.0 with 10%hydrochloric acid. After 18 hours at room temperature (22-'25 C.), theproduct was washed thoroughly with warm water and dried. The yield ofcopolymer amounted to 11.9 parts which constitutes a 19% conversion ofmonomer to unextractable polymer.

Example 4b Ten parts of polyvinyl alcohol were monothiocarbonated andwashed as described in Example 1b and suspended in an emulsionconsisting of 7.9 parts styrene, 1.0 part acrylonitrile, 2.0 partsTween-85, 50 parts water and 3.0 parts 30% hydrogen peroxide andadjusted to a pH of about 5.0 with 10% hydrochloric acid. After standingat room temperature for 18 hours, the product was removed from thepolymerization mixture and thoroughly washed with water. The product,oven dried, weighed 15.4 parts which constitutes an 81.6% yield ofthe'theoretical. Prolonged extraction of this material intrichloroethane indicated that 61.1% of the monomer which had beenconverted to polymer was nonextractable.

Example 5b Ten parts of polyvinyl alcohol were monothiocarbonated in themanner described in Example lb. The monothiocarbonated polyvinyl alcoholwas then washed thoroughly on a Biichner funnel with water to removesoluble by-products and then parts of 0.06 M lead acetate solution werepassed over and through the polyvinyl alcohol derivative to form leadpolyvinyl alcohol monothiocarbonate by metathesis. The lead product,after washing with suflicient water (ISO-200 parts) to remove excesslead ions, was dispensed in an emulsion such as that described inExample-4b.

After standing for 18 hours at room temperature, the copolymer wasremoved and washed well with water. Upon drying, the copolymer weighed14.05 parts, which constituted at 74.5% yield of the theoretical.Extraction with ethylene trichloride revealed that 66.8% of the monomerwhich had been converted to polymer was nonextractable.

Examples 6b-9b Ten parts of PVA were monothiocarbonated and converted tovarious polyvinyl alcohol monothiocarbonate salts by metathesis in themanner described in Example 5b. The monothiocar-bonate derivativcsiweresuspended for 18 hours in various polymerization mixtures before beingprocessed for yields.

1 7 Some of the results, representative of the various polyvinyl alcoholmonothiocarbonates and polymerization media used are listed below:

Percent Ex Cation Monomer Proce- Percent nonexdure yield tractablepolymer 6b Zinc. Acrylonitrile Ex. 1b 70. 8 61. 8 7b Cobal Ethylacrylate Ex. 21)... 67.4 66.8 8b Nickel Acrylamide Ex. 3 63. 5 100. 9b.Ferrousst lyihenelaoryloni- Ex. 4b.-. 73. 50. 1

Examples 1011-131) Ten parts of polyvinyl alcohol were placed in abeaker containing sufficient 0.0875 M sodium silicate solution to coverit completely for 10 minutes and then monothiocarbonated as described inExample 1b. Sodium monothiocarbonate salts as prepared above weresuspended in each of the following polymerization media with the resultof each shown:

Percent Percent non- Ex. Monomer Procedure yield extractable polymer 10bAcrylonitrile Example 1b 84. 5 83.0 11b Ethyl acrylate. Example 2!) 76.7 71. 3 12b-.. Acrylamide Example 3b 68. 2 100.0 13b.-.Styrene/aerylonitrile. Example 4b 79. 2 58. 7

Examples 1412-195 Percent Ex. Cation Monomer Proce- Percent nonexdureyield tractable polymer 1%.... Alumi- Aciylouitrile Ex. 11)... 71. 5 63.0

num. l5b Nickel .do Ex. lb... 65.0 49.9 16b Lead Ethy acrylate Ex.212... 76.8 72.9 1%.... Ferrous. do Ex. 21)... 81.5 63.1 18b. Zinc.Acrylamide Ex. 3b 60. 4 100.0 1912.... Cobalt. sttyiilcnelacryloni- Ex.lb. 71.7 60.8

Example 20b Five parts of polyvinyl alcohol were placed in a beaker andenough 0.25 M sodium carbonate was added to cover the polyvinyl alcohol.The mixture was allowed to stand at room temperature for about /2 hour,then filtered on a Biichner funnel. The alkaline-wet polyvinyl alcoholwas then monothiocarbonated as described in Example 1b and suspended ina solution of 5.0 parts acrylamide, 50 parts water and 1.5 parts of 30%hydrogen peroxide and'adjusted to a pH of about 5.0 with 10%hydrochloric acid. After 18 hours at room temperature, the product wasWashed thoroughly with warm water and dried. The yield of copolymeramounted to 7.53 parts, which constitutes a 50.6% conversion of monomerto unextractable polymer.

18 Example 21b Five parts of polyvinyl alcohol were placed in a beakercontaining sulficient 5% ammonium hydroxide solution to cover itcompletely. The mixture was allowed to remain at room temperature forabout /z hour, then filtered on a Btichner tunnel to remove excessammonium hydroxide solution and then monothiocarbonated as described inExample 1b. Immediately after washing, the polyvinyl alcoholmonothiocarbonate was suspended in an emulsion prepared from 4.0 partsacrylonitrile, 45 parts water, 0.5 part Tween and 1.5 parts of 30%hydrogen peroxide and adjusted the pH to about 5.0 with 10% hydrochloricacid. After standing at room temperature for 18 hours, the polyvinylalcohol copolymer was removed from the polymerization mixture andthoroughly washed with water, The product, oven dried, weighed 6.78parts, which constitutes a 74.2% yield of the theoretical. Prolongedextraction of this material with dimethylformamide indicated that 73.1%of the monomer which had been converted to polymer was nonextractable.

Example 22b Five parts of polyvinyl alcohol were placed in a beaker andenough 0.25 M methylamine was added to cover the polyvinyl alcohol.The-mixture was allowed to stand at room temperature for about /2 hourand then filtered on a Biichner funnel. The moist polyvinyl alcohol wasmonothiocarbonated as described in Example 1b and suspended in anemulsion consisting of 3.75 parts styrene, 0.25 part acrylonitrile, 45parts of distilled water, 0.5 part Tween- 85 and 1.5 parts of 30%hydrogen peroxide. The polymerization medium was adjusted to a pH ofabout 5 .0 with 10% hydrochloric acid. Upon standing at room temperaturefor 18 hours, the copolymerized polyvinyl alcohol was removed from thepolymerization mixture and thoroughly washed with water. The driedproduct weighed 6.57 parts, which constitutes a 73.4% yield oftheoretical. Prolonged extraction in ethylene trichloride indicated that64.7% of the monomer which had been converted to polymer could not beextracted.

Example 2312 Five parts of polyvinyl alcohol were placed in sufficient0.0875 M sodium sulfide to cover it completely. The mixture was allowedto stand at room temperature for about /2 hour, then filtered on aBiichner funnel and monothiocarbonated as described in Example lb.Immediately after Washing, the sodium polyvinyl alcoholmonothiocarbonate was added to an emulsion prepared from 4.5 parts ethylacrylate, 45 parts water, 0.2 part Tween85 and 1.5 parts of 30% hydrogenperoxide. The polymerization mixture was adjusted to a pH of about 5.0with 10% hydrochloric acid. After 18 hours at room temperature, thepolyvinyl alcohol copolymer was washed with water and dried. Thecopolymeric product amounted to 7.05 parts, which constitutes a 74.0%yield of the theoretical, Prolonged extraction of the product withacetone indicated that 86.3% of the monomer which had been converted topolymer could not be extracted.

Example 24b Five parts of polyvinyl alcohol were monothiocarbon ated asdescribed in Example 23b and converted by metathesis to cobalt polyvinylalcohol monothiocarbonate by substituting 0.06 M cobalt chloride for0.06 M lead acetate as described in Example 5b, and then suspended in anemulsion prepared from 3.75 parts styrene, 0.25 part acrylonitrile, 45parts water, 0.5 part Tween85 and 1.5 parts of 30% hydrogen peroxide.The polymerization mixture was adjusted to a pH of about 5.0 with 10%bydrochloric acid.

After standingat room temperature for 18 hours, the copolymer wasremoved from the polymerization medium and thoroughly washed with water.The product, oven dried, weighed 6.55 parts, which constitutes a 72.8%yield 19 of the theoretical. Prolonged extraction of this material withethylene trichloride indicated that 61.2% of the monomer which wasconverted to polymer could not be extracted.

Example 25 Ten parts of hydroxyethyl cellulose (Rayonier, Ethylose F)were soaked in 1% sodium hydroxide solution for about 5 minutes andmonothiocarbonated as described in Example 1b, This monothiocarbonatederivative was then suspended in an emulsion prepared from 16.0 partsacrylonitrile, 80 parts water, 2.0 parts hydrochloric acid, 0.5 partTween85 and 3.0 parts of 30% hydrogen peroxide. After 20 hours, thecopolymerized hydroxyethyl cellulose was washed well with water. Theproduct, oven dried, weighed 15.6 parts which, constitutes a 60.0% yieldof theoretical. Prolonged extraction with dimethylformamide indicatedthat 75.0% of the monomer which had been converted to polymer could notbe extracted.

Example 26b Five parts of ethyl cellulose (Type N-lO-S Hercules) weresoaked in 0.25% sodium hydroxide solution for about 5 minutes andmonothiocarbonated as described in Example 1b. This monothiocarbonatederivative was then suspended in an emulsion prepared from 3.75 partsstyrene, 0.25 part acrylonitrile, 20 parts water, 0.3 part Tween-85, 2parts 10% hydrochloric acid and 1.5 parts of 30% hydrogen peroxide.After 60 hours at room temperature, the copolymer was washed with waterand dried. The product weighed 6.00 parts, which constitutes a 67% yieldof the theoretical.

Example 27b Ten parts of cellulose acetate staple were placed in abeaker containing 200 parts of 0.75 M sodium hydroxide solution forabout hour and then monothiocarbonated as described in Example 1b. Themonothiocarbonate salt was suspended in a solution consisting of 10parts acrylamide, 90 parts water, 2 parts 10% hydrochloric acid and 3.0parts of 30% hydrogen peroxide. After 60 hours at ambient temperature,the copolymerized cellulose was washed well with Water and dried. Theproduct weighed 7.9 parts and was found to contain 5.92% nitrogen whichindicates at 24% conversion of monomer to unextractable polymer (2.4parts polyacrylamide).

Example 28b-32b A number of 10-part samples of polyvinyl alcohol weretreated and reacted in the manner described in Example 1b with theexception that a variety of monomers were substituted for acrylonitrile.The results of these reactions are tabulated below:

Examples 3312-35 b A series of 5-part samples of polyvinyl alcohol weretreated and reacted in the manner described in Example 20 9b. Variousmonomers were used in place of styrene acrylonitrile and the results areshown below:

Tween was omitted in this reaction.

The usefulness of the products which may be prepared by the practice ofthis invention is quite evident. To one knowledgeable in the propertiesof synthetic polymers and copolymers, innumerable combinations ofmonomers and synthetic substrates readily suggest themselves as havinguseful and novel properties. By way of example, improved celluloseacetate and polyvinylalcohol fibers may be obtained by thecopolymerization of these substrates with such monomers asacrylonitrile, various alkylarylates, and styrene. Adhesives withimproved bonding ability result from acrylic or methacrylic acidcopolymers of hydroxyethylcellulose and polyvinyl alcohol. Celluloseacetate copolymers of ethyl acrylate is a fine water resistant bondingagent for nonwoven fabrics. Copolymers of acrylic acid orN,N-diethylarninoethylmethacrylate with various hydroxylated, syntheticsubstrates constitute useful cationic and anionic ion-exchangematerials. Styrene, butylacrylate and stearylacrylate copolymers ofthese substrates, to name only a few, find use as molding powders.

The herein-described graft polymerization inventions utilizing thioatedsubstrate can be defined as a process of producing a copolymer ofethylenicaly unsaturated compounds and thioated substrates as definedherein which comprises reacting a water insoluble thiocarbonatederivative of a synthetic polymer as defined herein, via peroxidicfree-radical initiation, with at least one ethylenically unsaturatedmonomer, preferably wherein (a) The thiocarbonate derivative isemployed, or

(b) The monomer is uniformly distributed in water, e.g., as a solution,an emulsion or as a mechanical dispersion, or

(c) The reaction media contains a wetting agent, or

(d) The thiocarbonate derivative is an alkali-metal salt, e.g., thesodium salt, or

(e) The thiocarbonate derivative is a salt of at least one metalselected from the group consisting of metals in the Periodic TablesGroups Ib, IIa, IIb, IIIa, IIIb, IVb, Vb, VIb, VIIb, VIII, Ge, Sn, Pb,and Bi; or

(f) The thiocarbonate derivative is a salt of at least one member of thegroup consisting of ammonia, primary, secondary, tertiary amine,quaternary ammonium, tertiary sulfonium, quaternary phosphonium,quaternary arsonium and quaternary stibonium salt, e.g., a salt isformed from a trimethylsulfonium precursor or the salt is tetrakis(hydroxymethyl) phosphonium; included in the above-described inventionsare the products obtained by the process defined by (f); or

(g) The monomer is selected from the group consisting of CHR=CHR; H C=CRR C=CR and "R\\ R=oR wherein R is selected from at least one member ofthe group consisting of (1) hydrogen; (2) alkyl group; (3) alkene group;(4) alkyne group; (5) aryl group; (6) substituted aryl group; (7) anelectronegative group; (8) an alicyclic group; (9) a heterocyclic group;(10) a substituted heterocyclic group; (11) a carbalkoxy group of thegeneral formula 21 wherein R is selected from the group consisting ofhydrogen, R, hydrocarbons of from 1 to 18 carbon atoms, and substitutedhydrocarbons of from 1 to 18 carbon atoms; (12) groups of the generalformula Ril (13) groups of the general formula ll R-CO (14) groups ofthe general formula R"-O; (15) groups of the general formula RzNCwherein R" is selected from at least one member of the group consistingof hydrogen, R, and R, hydrocarbons of from 1 to 18 carbon atoms,substituted hydrocarbons of from 1 to 18 carbon atoms, and aliphaticgroups of from 1 to 18 carbon atoms, especially wherein thethiocarbonate derivative is the dithiocarbonate derivative; or

(h) The thiocarbonate derivative is a salt selected from at least onemember of the group consisting of ammonia, primary, secondary, tertiaryamine, quaternary organic ammonium, tertiary sulfonium, quaternaryphosphonium, quaternary arsonium, quaternary stibonium, lithium, sodiumand potassium, or a water-soluble salt of at least one metal selectedfrom the groupconsisting of metals in the Periodic Tables Groups Ib,Ila, IIb, Illa, IIIb, IVb,

Vb, VIb, VIIb, VIII, Ge, Sn, Pb and Bi, which is reacted- With themonomer dispersed in an aqueous solution, especially wherein the monomeris acrylamide, acrylic acid, acrylonitrile, a mixture of styrene and'Z-ethylhexylacrylate or a mixture of acrylonitrile and styrene,especially wherein the thiocarbonate salt is a. dithiocarbonate salt andmore preferably wherein the dithiocarbonate salt is selected from atleast one member of the group consisting of an alkali metal, ammonia andwater-soluble amines, or is a ferrous, or ferric salt; included in theinvention are the products obtained according to the process defined in(h), especially the products wherein the salt is ferrous, sodium orammonium; or

(i) The thiocarbonate derivative is mixed with the monomer in an aqueoussolution in which the monomer is uniformly distributed, the peroxidicfree-radical initiator is added to the solution containing thethiocarbonate salt derivative and the monomer, the reaction is allowedto proceed at a temperature of from 0 to 100 C. of from about 3 minutesto about 96 hours, and the formed copolymer is thereafter recovered fromthe solution, or;

(j) The thiocarbonate derivative is produced by reacting thecorresponding water-insoluble substrate, which is wet with an aqueoussolution of a base, with carbon disulfide or carbonyl sulfide,especially carbon disulfide; the base preferably being a metal base,more preferably an alkali-metal hydroxide and especially sodiumhydroxide; desirably by the steps of wetting the polymeric material withan aqueous solution of the selected base, separating the solution fromthe polymer wet with base, and exposing the polymer wet with base to thevapors of carbon disulfide or carbonyl sulfide or a solution thereof inan inert solvent; desirably also performing the last of the aforesaidsteps substantially immediately after Wetting the polymeric substratewith the base; and desirably also thereafter washing the resultingcopolymer with water to remove any excess monomer and solubleby-products of the reaction; plus all possible combinations of theabove.

What is claimed is:

1. The process which comprises the steps of wetting with an alkalinesolution a Water-insoluble, synthetic, hydroxyl group-containing polymeror a water-insoluble, synthetic polymer containing a group hydrolyzableto a hydroxyl group; bringing the alkaline-wet polymer in intimatecontact with carbon disulfide or carbonyl sulfide to 22 produce awater-insoluble thioated derivative of the poly mer; washing theresulting thioated derivative to remove the water-soluble by-products ofthe thioate formation or thioate substrate decomposition; and reactingthe resulting thioated derivative, via free radical initiation, with atleast one ethylenically unsaturated monomer.

2. Theproducts obtained according to the process of claim 1.

3. The process acocrding to claim 1 wherein the thiocarbonate derivativeis a dithiocarbonate derivative.

4. The process according to claim 3 wherein the synthetic polymer is acellulose ester of cellulose ether.

5. The products obtained according to the process of claim 4.

6. The process according to claim 3 wherein the synthetic polymer is apolymer of an ethylenically unsaturated monomer.

7. The process according to claim 3 wherein the synthetic polymer is amember of the group consisting of polyvinyl alcohol, polyvinyl acetate,a copolymer of vinyl acetate and a different copolymerizable olefinicmonomer, the hydrolysis products thereof, polymers ofhydroxyethylacrylate, polymers of hydroxyethylmethacrylate, and polymersof hydroxypropylacrylate and hydroxypropylmethacrylate.

8. The products obtained according to the process of claim 7.

9. The process according to claim 1 wherein the graft polymerization isconducted in an aqueous polymerization system in which the monomer isuniformly distributed.

10. The process according to claim 9 wherein the thiocarbonatederivative is adithiocarbonate.

11. The process according to claim 9 wherein the peroxidic initiator ishydrogen peroxide.

12. The process according to claim 9 wherein the reaction is conductedin water.

13. The process according to claim 12 wherein the reaction is conductedin the presence of at least one member of the group consisting of anemulsifying agent sulficient to form a stable emulsion and a wettingagent.

14. The process according to claim 1 wherein the thiocarbonatederivative is a salt of at least one member of the group selected fromammonium, primary, secondary, tertiary amine, quaternary ammonium,tertiary sulfonium, quaternary phosphonium, quaternary arsonium,quaternary stibonium, lithium, sodium, potassium, Ge, Sn, Pb, Bi andmetals in the Periodic Tables groups Ib, Ila, IIb, IIIa, 111]), IV b,Vb, VIb VIIb, and VIII.

15. The process according to claim 14 wherein the thiocarbonatederivative is a dithiocarbonate derivative.

16. The process according to claim 14 wherein the salt is an ammoniumsalt.

17. The process according to claim 14 wherein the salt is the sodiumsalt.

18. The process according to claim 14 wherein the salt is the ferroussalt.

19. The process according to claim 1 which includes the step ofconverting a thiocarbonate salt of the synthetic polymer metatheticallyto another salt thereof.

20. The process according to claim 19 wherein the salt convertedmetathetically to another salt is the sodium or ammonium salt.

21. The process according to claim 19 wherein the metatheticallyproduced salt is the salt of a metal selected from the group consistingof Ge, Sn, Pb, Bi and metals in the Periodic Tables Groups Ib, 11a, 11b,111a, IIIb, IVb, Vb, VIb, VIIb, and VIII.

22. The process according to claim 1 wherein the thiocarbonatederivative is a thiocarbonate salt produced by reacting metathetically athiocarbonate salt of at least one member of the group consisting ofammonia, primary, secondary, tertiary amine, quaternary ammonium,tertiary sulfonium, quaternary phosphonium, quaternary arsonium,quaternary stibonium, lithium, sodium and potassium with a water-solublesalt of at least one metal selected 23 from the group consisting of Ge,Sn, Pb, Bi and metals in the Periodic Tables Groups Ib, 11a, 1111, 111a,IIIb, IVb, Vb, VIb, VIII), and VIII.

23. The process according to claim 22 wherein the thiocarbonatederivative is a dithiocarbonate derivative.

24. The process according to claim 1 wherein the monomer has anethylenic group at an unsubstituted terminal carbon atom.

25. The process according to claim 24 wherein the thiocarbonate is adithiocarbonate salt.

26. The process according to claim 1 wherein the monomer is at least onemember of the group consisting of CHR CHR; H C==CR and R C=CR wherein Ris selected from at least one member of the group consisting of (1)hydrogen; (2) alkyl group; (3) alkene group; (4) alkyne group; (5) anaryl group; (6) an alicyclic group; (7) a heterocyclic group; (8) acarbalkoxy group of the general formula O l (9) groups of the generalformula 0 H RG 10) groups of the general formula (11) groups of thegeneral formula R"O-; and (12) groups of the general formula wherein Rand R" are selected from a member of the 24 group consisting of hydrogenand hydrocarbons of from 1 to 18 carbon atoms.

27. The process according to claim 26 wherein the thio carbonatederivative is dithiocarbonate.

28. The process according to claim monomer is acrylic acid.

29. The process according to claim monomer is acrylonitrile.

30. The process according to claim monomers are acrylonitrile andstyrene.

31. The process according to claim monomer is vinylidene chloride.

32. The process according to claim monomer is acrylamide.

33. The process according to claim 1 wherein carbon disulfide isemployed.

34. The process according to claim 1 wherein the alkaline solution is analkali-metal hydroxide solution.

35. The process according to claim 1 wherein the synthetic polymer iswet with aqu ous sodium hydroxide of up ,to 0.05 molar concentration andthe alkaline-wet synthetic polymer is contacted with carbon disulfide.

26 wherein the 26 wherein the 26 wherein the 26 wherein the 26 whereinthe No references cited.

WILLIAM H. SHORT, Primary Examiner.

J. NORRIS, Assistant Examiner.

1. THE PROCESS WHICH COMPRISES THE STEPS OF WETTING WITH AN ALKALINESOLUTION A WATER-INSOLUBLE, SYNETHETIC, HYDROXYL GROUP-CONTAININGPOLYMER OR A WATER-INSOLUBLE, SYNTHETIC POLYMER CONTAINING A GROUPHYDROLYZABLE TO A HYDROXYL GROUP; BRINGING THE ALKALINE-WET POLYMER ININTIMATE CONTACT WITH CARBON DISULFIDE OR CARBONYL SULFIDE TO PRODUCE AWATER-INSOLUBLE THIOATED DERIVATIVE OF THE POLYMER; WASHING THERESULTING THIOATED DERIVATIVE TO REMOVE THE WATER-SOLUBLE BY-PRODUCTS OFTHE THIOATE FORMATION OR THIOATE SUBSTRATE DECOMPOSITION; AND REACTINGTHE RESULTING THIOATED DERIVATIVE, VIS FREE RADICAL INITIATION, WITH ATLEAST ONE ETHYLENICALLY UNSATURATED MONOMER.